Means for supplying liquid fuel to internal-combustion engines



J. M KECHNIE MEANS FOR SUPPLYING LIQUID FUEL TO INTERNAL COMBUSTIONENGINES Filed Feb. 28, l921 2 sheeti-heet l Dec. 1924- 1,520,833

J. M KECHNIE MEANS FOR SUPPLYING LIQUID FUEL TO INTERNAL COMBUSTIONENGINES- Filed Feb. 28, 1921 2 Sheets-Sheet 2 Patented Dec.i30, 1924.

UNITED STATES PATENT OFFICE.

JAMES MGKECHNIE, OF BARROW-IN-FURNESS, COUNTY OELANGASTER, ENGLAND, AS-SIGNOR ,TO VIC-KERS LIMITED, OF WESTMINSTER, ENGLAND.

MEANS FOR SUPPLYING LIQUID FUEL TO INTERNAL-COMBUSTION ENGINES.

, Application filed February 28, 1921. SeriaiNo. 448,498.

To all whom it concern: Be it known that I, JAMES MGKECHNIE, a

subject of the King of Great Britain,- resid-v ing at Naval Constrhction\Vorks, Barrowin-Furness, 1n the county of Lancaster, England, havelnvented new and useful Improvements in or Relating to Means for Sup-'plying Liquid. Fuel to Internal-Combustion Engines, of which thefollowingis a. specification.

This invention relates to means for .sup plying liquid .fuel to internalcombustion engines of the type in which liquid fuel is injected at highpressure and without the aid of injecting air into the compression spaceof the engine cylinder. For such injection .rcsilient accumulatorpressure is desirable and this has usually been obtained hitherto bypumping the fuel'against resilicnt pressure in a special chamber or ac-'cumulator associated with the fuel supply pipe.

According to this invention the fuel is delivered by a pump into a tubeor hollow rail which conveys the fuel to the injection valve or valvesof the cylinder or cylinders of the engine, the volume and proportionsof the said tube or rail being such that the tube or rail constitutes aresilient accumulator which under the pressure produced by the pumpaccommodates the required fuel charge and maintains the pressure at theinjection valve or valves at the high level required during the valveopening. The tube is of considerable length, necessarily so in amulti-cylinder engine (where it extends across a number of cylinders andis then sometimes referred to as the rail), and yields throughout itslength-to provide the required charge volume. Q It may be cylindrical'incross section, or oval or flattened to provide for such yielding as maybe necessary while possessing sufficient strength to withstand thepressure. With this arrangement .no special accumulator isprovided asthe tube or rail which delivers the fuel to the engine itselffurnishesthe desired accumulator effect owing to its substantial volume, inconjunction with the change in volume of the fuel itself due to the highpressure of injection. Thetube' may be mounted so as to extendlongitudinally under the fuel pressure as well as expand transversely,for which ur ose a straight rail or tube may haye closed ends, the. fuelbeing led to each in ection valve through a branch pipe.

The pump may be arranged to raise the fuel pressure gradually to thehigh pressure required at the tube or rail, by exercising achoklngaction on a fuel escape during the first part of the plungerdelivery stroke.

The pump may be operated synchronously with the engine so that the fuelinjection periods occur during the pump delivery strokes, or the-pumpmay be partially or completely out of step with the injection periods.In the former case the tube or rail need not provide forso large a fuelcharge as in the latter case.

In order that the said invention may be clearly understood and readilycarried into multi-cylinder engine provided with'the imeffect, the samewill now be described more fully with reference to theaccompanyingproved fuel supplying means; various details shown in.Figure 2 are omitted from Figure 1 for the sake of clearness.

'Figure3 is a diagrammatic front elevation I of an engine showing amodified arrange-- ment of the fuel supply.

Figure 4 is a similar diagram showing a further modification, and Figure5 is a diagram showing theapplication of the invention to a singlecylinder engine.

Referring first toFigures 1 and 2,'A, A

are the engine cylinders-each provided with an injection valve B ofknown type, under the control of a valve operating cam C, the injectionvalve controlling the power of the engine by varying the period duringwhich the liquid fuel unmixed with air is injected into the cylinderunder the high pressure required. D is'the fuel pump, a four plungerpump being shown in Figure 1, the fuel being introduced into the pumpthe main tube or. rail extending longitudinally across the cylinders ofthe engine, this rail being connected to the pump by the tube F andsupplying fuel to each of the injection valves 13 through the small borebranch pipes e for each of which is prothrough the pipes d at thesuction side from vided a cut-off cook or valve 6, a similar I cook orvalve 6 being provided at the end of the tube F.

The injection valve B controls the power of the engine, since the objectof the 51CC11- mulation of the fuel under extremely high pressure in therail and the connecting pipes 15 to maintain ,such pressure at the valvethroughout the period of in ection with as small a drop as is feasiblewithout excessive lever 72 of the valve B, so as to raise the latteragainst the pressure of its spring I) and allow of the, entry of liquidfuel into the working space a of the cylinder A. Under the very highpressure of the fuel in the rail or tube system the fuel breaks into afine spray as soon as itenters the cylinder.

The period during which the injection valve B is opened at eachinjection is varied in known manner by angularly adjusting the eccentricfulcrum pin g so as to bring the cam roller g away from or closer to thecam C which is mounted on the cam shaft 0. This is conveniently done bythe hand lever H of usual type connected through the rod 6 to the leverj on the common control shaft J which at each cylinder carries a lever Kattached to the lower end of a pair of rods L, L connected together by abalancing 'leverl, the upper end of the rod L being at-. tached to anarm 9 on the. fulcrum shaft G. The position of the lever H thereforedetermines the angular position of the fulcrum pin 9. 1

Any individual cylinder can be cut out independently of the commoncontrol lever H by the separate operation of the lever j,

'WlllCh is shown of hell crank form and 1s not rigidly fixedto thecommon control shaft but can be disconnected at will and when turnedinto cut out position can be held by the stop 7' engaging the fixedcatch a on the bracket of carrying the shaft J and secured .on the sideof the, engine.

As the pressure in the rail or tube supply system is extremely high(usually from 2000 lbs. to 6000 lbs. per square inch, but it may beconsiderably greater) it is desirable that the pump D should not beexposed to the shock involved in suddenly raising the pressure to thislevel. For the purposeofproviding a relatively gradual rise during thestroke of a pump plungerthe fuel is allowed to escape during the firstpart of the delivery stroke through a passage or channel which gives anincreasing choking effect until on complete closure the full pumppressure is attained. This is effected in the pump shown by providing(see Figure 2, the pump details being omitted in Figure 1) a suctionvalve M which can be held open mechanically. by a rod m under thecontrol of a small lever m operated through the connecting rod m by thelever m connected to the pump plunger 05 at the endopposite to the rod mand carried on the adjustable fulcrum n provided at the end of asupporting rod n mounted on the lever arm N connected at its. outer endto the end of the pump control lever O by the adjustable connecting rod0. The lever 0 moves over the notched quadrant 0 and is provided with acatch 0 by which it is held in adjusted position.

The levers m and m both give large leverage so that as the plunger rod03 moves up for the delivery stroke it gives rise to a much smallermovement of the other end of the lever m and this in its turn gives amuch reduced movement to the adjustable stud m on the lever m which studmeets the rod m controlling the closing movement of the valve Mr Thus asthe plunger (i rises the stud m is lowered and allows the suction valveM to close so slowly that the passage for escape of the fuel back to thesuction side of the pump gives an increasing choking action beforefinally allowing the valve to close. The pump pressure thus graduallyattains to the full pressure in the fuel supply system, whereupon fuelis delivered into the pipes leading to the cylinders and maintains thepressure of supply as the fuel is discharged through the injectionvalve. Owing to the capacity of the fuel supply system, including therail E and the associated pipes, and the resilient accumulator effectthere is no need for the pumpv delivery strokes to synchronize with theperiods of injection of the various cylinders so that the pump can, ifdesired, be driven independently of the engine. The effective stroke ofthe pump is varied by altering the position of the adjustable, fulcrum nby means of the control lever t), the position of the fulcrumdetermining the point in the pump stroke at which the suction valve M isallowed to close. Earlier closing gives a longer effective deliverystroke and later closing reduces the amount of fuel delivered.

In the pump shown (see Figure. l) the two pump casings are connected bythe short branch pipes f to the main tube F through the cock or'valve f.The rail E. to which the tube F leads is supported in the brackets abelonging to the variouscylindersand is free to expand longitudinally inthe brackets, the ends of the rail having connected to them respectivelya small bore tube 6 fitted with discharge cocks e and a pressure gaugetube 6 A tube 6 may also be provided to connect to a rail for asecondset of cylinders.

.As the rail E is free to expand longitudinally under the pressure uponits ends the I tiallv increased by the extension of the rail.

resilient accumulator volume is substanso that without unduly enlargingthe diam: eter ample accommodation for the charges of fuel for thevarious cylinders is ensured, taking into account the compression of thefuel itself.

In the diagram, Figure 3, the arrangement is substantially similartothat already described, but the pump D is placed at one end of theengine and the tube F leads from the pump to the end of the rail E,which is placed high, upso that the'branch pipes 0 leading to the valvesB are short.

In Figure 4 the pum is also at'the end of the engine, but the rail 4 isplaced low down and between the rail and the small branch pipes aleading to the valves are large diameter tubes a forming branchingextensions of the rail and providing substantial additional accumulatorvolume as close as possible to the injection valves.

Figure 5 shows the application of the system to a single cylinderengine. In this case there is no longitudinal rail extending across anumber of cylinders and the accumulator volume required is obtained bycon- I necting the pump D to alarge diameter fuel Conducting tube orpipe E arranged to give sufficient resilient yield to take in a chargefor the single cylinder and to maintain the high pressure independentlyof the direct pressure due to the pump, during the opening of theinjection valve.

. The conditions in the tubular fuel con ducting and accumulator systemdiffer to some extent according to whether or not the fuel pump is timedin accordance with the engine stroke so that-the injection of the fueloccurs during the delivery stroke of the pump. If the pump synchronizeswith the firing, stroke the accumulator charge necessary to maintain ahigh pressure at the valve may be a comparatively small fraction of acomplete cylinder charge, though much greater than would be accommodatedb the thick, small-bore tubes generally emp oyed to conduct the liquidfuel to the cylinders.

Where synchronization of the pump and firing strokes is arranged for thetube or rail may accommodate (within a range of pressures of say about1500 lbs. per square inch,

' for example from 2500 lbs. to 4000 lbs.)

only one tenth ofa full cylinder charge but preferably the tube is of.such volume and proportions as to-allow of the resilient accu mulationunder such range of pressures of a substantially larger fuel volume,say, a

quarter, a third, a half or more of afull single cylinder charge. Thepump is not usually adapted-to deliver exactly in synchronism with theinjection period, since the fuel charge has to be injected into thecylinder during a very short period of opening of the valve and unlessthere is a substantial accumulator efiect provided for it is difficultto maintain the required high pressure of injection during therapiddischarge. The tube or rail must, therefore, for the purposes of thisinvention, compensate for any differences between the fuel dischargethrough the injection valve and the rate ofdelivery from the pump, so asto prevent the pressure at the injection valve falling below a highlevel.

Where the' pump is driven (as would commonly be the case in a multi-clinder engine) without synchronizing wit the firing strokes, orsynchronizing only at intervals,

'the tube or rail must accommodate a much ering into a tube or railsystem having a capacity of 256 cubic inches at. a maximum pressure ofabout 4000 lbs. per square inch.

The capacity of the tubular fuel conducting system (256 cubic inches) ismany times that which has been employed merely to lead the fuel from thepumpto the cylinders and in the engine referred to the rise and fall ofpressure due to the admission and withdrawal of the charge of about 0.8cubic inch is in the neighbourhood of 1000 lbs. per square inch.

The supply of a full charge of fuel to a cylinder when the pump deliverystroke is entirely out of phase with the firing stroke is thereforeensured and ample margin is pro vided for any probable irregularities inthe action of the pumpor of an injection valve. The above engme is onein which the pump is out of synchronlsm with the eugine, but even' inengines with approxim mately synchronous pump delivery and fir ingstrokes it is desirable to employ a large tube volume, in case ofpartial or complete failure of a pump stroke due to leakage of a gland,dirt under the valve or accidental admission of air or other cause; orto. i rregularities of action at the injection valves. Such largeaccumulator volume as is given above is however not essential, althoughper haps desirable, where the pump operates synchronously with theengine.

What I claim and desire to secure by Letters Patent of the United Statesis 1. In a multicylinder internal combustion engine, a plurality ofcylinders, an injection valve for liquid fuel unmixed with air at eachcylinder, mechanism .for opening said valves in the required order andfor regulated periods, a fuel supply conduit for a plurality ofcylinders leading to each of said injection valves, a liquid fuel pumpconnected to the said common fuel supply conduit, said fuel supplyconduit having relatively thin walls and relativelylarge'cross-sectional area for a substantial portion of its length togive sufficient elasticity to distortunde'r the pressure of the fuel inthe supply conduit to increase the capacity of the fuel supply conduit,whereby upon theopening of one of said injection valves the fuel supplyconduit contracts sufficiently to inject a charge of fuel into one ofthe said cylinders without the use of any special accumulators in thefuel supply system to obtain the proper injection of a charge offuel'into one of the said cylinders. w

2. In a multicylinder internal combustion engine, a plurality ofcylinders, an injection valve for liquid fuel unmixed with air at eachcylinder, mechanism for opening said valves in the required order andfor reg-.

ulated periods, a fuel supply conduit for a plurality of cylindersleading to each injection valve, a liquid fuel pump connected to saidfuel supply conduit, means for ,actuatingsaid pump to pumpfuelintermittently into said conduit out ofasynchronism with I theopening of the injection valves, said conduit having relatively thinwalls and relatively large cross-sectional area for a substantialportion of its length to give suiiicient elasticity to distort under thepressure of the fuel in said conduit when said injection valves areclosed to increase the capacity of the fuel supply conduit and tocontract ,upon the opening of one of said injection,

valves to inject a charge of fuel into one of said cylinders without theuse of any special accumulators in i the fuel supply system to obtainthe proper injection of a charge of fuel into one of the said cylinders.

3. 'In a'multicylinder internal combustion engine, a plurality ofcylinders, an injection valve for liquid fuel unmixed with air at eachcylinder, mechanism for opening said valves in the required order andfor regulated periods, a fuel supply conduit for a plurality ofcylinders leading to each injectionvalve, a liquid fuel pump connectedto the said fuel supply conduit, means for actuating said pump topump-fuel intermittently into the fuel supply conduit out of synchronismwith the opening of the injection valves, said pump having a fueldischarge passage and means for slowly closing said discharge passageduring the first part of the delivery stroke of said pump to exercise anincreasing choking action on the fuel and raise the pump pressuregradually to the limit required to inject the fuel into the pressure ofthe fuel Within'it to increase its capacity when the injection valvesare closed and upon the opening of one of said in ection valves tocontract and in ect a charge of fuel into one of said cylinders withoutthe use of any special accumulators in the fuel supply system to obtainthe proper injection of a charge of fuel into one of thesaid cylinders.

4. In a multicylinder internal combustion engine, a plurality ofcylinders, an injection valve for liquid fuel unmixed with air,mechanism for opening said valves in the required order and forregulated periods, a fuel supply tube common to all the cylinders,connections from said tube to each injection valve, and a liquid fuelpump connected to said common fuel supply tube, said tube havingrelatively thin walls and relatively large cross-sectional area for asubstantial portion of its length to give sufficient elasticity todistort under the pressure of the fuel inthe tube and toCOIltl'iOilWllGH one of the said injection valves is opened to inject acharge of fuel into one of the cylinders without the use .of any specialaccumulators in the fuel supply system to obtain the proper injection ofa charge of fuel into one of the said cylinders.

5. In a' multicylinder internal combustion engine, a plurality ofcylinders, an injection valve for liquid fuel unmixed with'air at eachcylinder, mechanism for, opening said valves in the required order andfor regulated periods, a fuel conducting tube common to a plurality ofcylinders, supporting means for said tube permitting free expansion andcontraction of said tube longitudinally and transversely, connections vfrom said tube to each injection valve, a liquid fuel pump connected tosaid fuel conducting tube, said fuel conducting tube having relativelythins walls and relatively large cross sectional area for a substantialportion of its length to give sufficient elasticity to distort under thepressure of the fuel within the. same to increase the fuel carryingcapacity of said'tube and upon the opening of one of said injectionvalves to contract and inject a charge of fuel intoone of said cylinderswithout the use of any special accumulators in the fuel supply system toobtain the proper injection of a charge of fuel into one of the saidcylinders.

JAMES McKEOHNIE.

